The present invention relates to a light-sensitive composition which is spectrally sensitized and highly sensitive in a broad wavelength region from the ultraviolet region to the visible region, and comprises a novel aromatic diazonium compound.
Aromatic diazonium compounds have come to be used in various light-sensitive compositions. For example, their photodecomposability has been utilized in combination with couplers in dye image formation, and, their photocrosslinkability or light induced insolubility has been widely used with monomers or binders in the field of lithographic plates, proof mask films, and resists. The use of these kinds of light-sensitive compositions is given in J. Kosar, Light Sensitive Systems (John Wiley & Sons, 1965), and A. Reiser, Photoreactive Polymers (John Wiley & Sons, 1989).
However, with respect to light sensitive compositions utilizing aromatic diazonium compounds, no system has yet been proposed having high light-sensitivity from the ultraviolet to the visible wavelength region.
In the above light-sensitive compositions, the photodecomposable aromatic diazonium compounds generally require very great energies to photodecompose, and their light-sensitive wavelengths are equal to or shorter than wavelengths of the blue portion of the visible spectrum. For this reason the scope of light-sensitive compositions which can be used ends with low sensitivity materials and those which are exposed with ultraviolet rays.
For these reasons, vigorous research has been applied to photosensitization in the visible region of photodecomposable aromatic diazonium compounds. For example, it is known that specific dyes having riboflavin, porphyrin, chlorophyl, etc. are spectral sensitizers. Other sensitization methods are proposed by E. Inoue in "Photographic Science and Engineering", volume 17, pages 28 and 268, and volume 18, page 25, in which systems are proposed having a mixture of sensitizing color elements, such as methylene blue, etc., and p-toluene sulphonic acid, among other activators.
However, present methods, because they have such defects as not yet having sufficient sensitivity, having poor stability, not allowing free selection of the spectral wavelength region, etc., have not arrived at the stage where they can actually be incorporated into products.